Synergistic mixture of parathion and its ortho-isomer



United States Patent 3,155,570 SYNERGESHC MDQTURE F PARATEHQN AND ITS ORTHO-ISOMER Gerhard Schrader, Wuppertal Cronenherg, Germany, assignor to Farhenfabriken Bayer Airtiengeselisehaft, Leverlrusen, Germany, a corporation of Germany No Drawing. Filed June 19, 1962, Ser. No. 293,467 Claims priority, application Germany July '7, 1961 2 Claims. (Cl. 167-3tl) Killing of aphids (M.

Compound persicae) after 24 hours Percent It has now surprisingly been observed that new active agents are obtained by combining the paraand orthocompounds which show the same insecticidal activity as the pure paracornpounds.

The mixing proportion within which the unexpected activity increase has been ascertained amounts to at least about one part of para-compound per part of ortho-compound. If more of the ortho-compound is present in the mixture of active agents according to the invention, the activity decreases more strongly so that no products of practical interest are obtained. If less than 20% of ortho-compound are present in the inventive mixture, the

3,155,570 Patented Nov. 3, 1964 lCQ synergistic effect is only of minor importance so that this represents about the lower limit of ortho-compound.

In the following the proportions of the activity of a mixture of of orthoand 50% of para-compound (I) is compared with pure para-compound (H) of the 0,0- diethyl-O-nitrophenyl thiono-phosphate.

Aphids (M. persicae) Compound killed after 24 hours The present invention is of great technical interest. As is well known, the preparation of para-nitrophenol yields at first a mixture of paraand ortho-compound. Hitherto, the ortho-nitrophenol had to be separated from the paracompound by a cumbersome and time-consuming process.

According to the present invention a raw product consisting of about 50%80% of paraand 20%-50% of ortho-nitrophenol can be used immediately for the production of parathione-like compounds, without a reduction of the insecticidal activity taking place. The establishment of the synergistic activity of the ortho-compound and the para-compound thus gives rise to an essential simplification of the technical production of pest control agents which contain parathione and rnethyl-parathione.

I claim:

1. A pest control composition containing an effective amount of a mixture of (A) a component selected from the group consisting of (1) 0,0-diethyl-O-p-nitrophenyl thionophosphate and (2) 0,0-dimethyl-O-p-nitrophenyl thionophosphate and (B) A component selected from the group consisting of (1) 0,0-diethyl-o-nitrophenyl thionophosphate and (2) 0,0-dimethyl-o-nitrophenyl thionophosphate wherein the ratio of A to B is about 1:1 parts by weight.

2. A pest control composition containing an elfective amount of a mixture of 0,0-diethyl-O-p-nitrophenyl thionophosphate, and 0,0-diethyl-o-nitrophenyl thionophosphate in the proportions by weight of about 1:1.

References (Cited in the file of this patent UNITED STATES PATENTS 

1.A PEST CONTROL COMPOSITION CONTAINING AN EFFECTIVE AMOUNT OF A MIXTURE OF (A) A COMPONENT SELECTED FROM THE GROUP CONSISTING OF (1) O,O-DIETHYL-O-P-NITROPHENYI THIONOPHOSPHATE AND (2) O,O-DIMETHYL-O-P-NITROPHENYL THIONOPHOSHATE AND (B) A COMPONENT SELECTED FROM THE GROUP CONSISTING OF (1) O,O-DIETHYL-O-NITROPHENYL THIONOPHOSPHATE AND (2) O,O-DIMETHYL-O-NITROPHENYL THIONOPHOSPHATE WHERE THE RATIO OF A TO B IS ABOUT 1:1 PARTS BY WEIGHT. 